The error message is useless when there is no info about where the error comes from. Check the full error message and show us all the lines you received. You may need to look into the logfile - most probably: 'log/development.log'.
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Arsen7Sep 6 '11 at 9:46

I'll post the exact message when I get home, but from memory the error log said rendered /layouts/forms.html.erb and then immediately after had an internal server error. I can put a logger inside the controller action and it logs just fine, but there wasn't a line number like there normally is when you get an error like this... just an internal server error.
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MsencenbSep 6 '11 at 16:38

Thank for your development.log. It looks "App.find..." is OK, but error happens at rendering the view. Does the forms/index.html.erb (or partial in it, or any helper which the erb file uses) has 'status' method? If yes like 'x.status', x should be nil so that why the error happened. By the way, is your routing (resources :apps do esources :forms end) correct? do you really need nested resource routing?
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Fumisky WellsSep 7 '11 at 9:07

Another comment. Maybe (at-mark)app is bad. When we see RoR source in gems directory, there (at-mark)app variable in Rack and ActionController. What happens when you change (at-mark)app to another instance variable like (at-mark)my_app and use it in the view? (BTW, at-mark here means @ to avoid this site's comment format)
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Fumisky WellsSep 7 '11 at 9:35

For internal server errors your application could not be started properly. You should check your server error log. It may give you insight as to what the problem is. If you, or a team member as the case may be, didn't make any changes that broke the application then you should check with your host. Perhaps they made changes to your environment that are causing an error.